This invention relates to an apparatus for spin welding one member to another. More particularly, it relates to a spin welding device which can accurately and consistently effect frictional engagement between a cap and a container at high production rates while compensating for numerous variables in the cap, container and machine design.
The friction-type welding apparatus of the type generally concerned with in this invention is described in U.S. Pat. Nos. 3,216,874; 3,220,908; 3,297,504; 3,316,135; 3,499,068 and 3,607,581. All of these patents describe the general mechanisms and procedures for friction welding two thermoplastic components together. However, these patents teach the formation of a container from two different flexible components and is unlike the present apparatus which is directed to the sealing of a rigid thermoplastic cap to a rigid thermoplastic container neck. Problems arise in spin welding equipment in that variables will exist in the container neck rib as well as the cap when frictional engagement is to be effected for purposes of sealing the cap to the rib. Further, tolerances in machine design do occur which when added to the previously referred to variables result in caps which do not adequately seal to the container. The prior art nowhere offers a solution to this problem and nowhere is there available a machine which can accomplish the foregoing mentioned sealing of an overcap on a semirigid container at a high capacity rate.
It is an advantage of the present invention to provide an apparatus for frictionally joining a cap to a container. Other advantages are an apparatus which can secure plastic cap members to plastic containers which will allow for tolerances in the cap and the container and effect a secure bonding; an apparatus which will perform the foregoing advantages at a high rate of speed; an apparatus which can orientate a cap member with the neck of a container in a secure manner so that the cap can be frictionally engaged on the container by rotating the cap member at a high rate of speed; and an apparatus which can spin weld a substantially thick thermoplastic cap member to a semirigid thermoplastic bottle which has a rather thin wall construction, is elongated in configuration, and filled with an irrigation solution.